When editing an event's alarm and clicking "Ok" w/o specifying any value for the "delay", we get a nice popup saying:

"heu"

From ./UI/WebServerResources/UIxReminderEditor.js, we have:

function onEditorOkClick(event) {
preventDefault(event);
if (parseInt($("quantityField").value) > 0) {
...
}
else
alert("heu");
}